The FAA on Tuesday issued a final rule amending Part 121 regulations governing drug and alcohol testing to clarify that “each person who performs a safety-sensitive function for a regulated employer by contract, including by subcontract at any tier, is subject to testing.” These amendments are necessary, the FAA said, because guidance has been conflicting for more than a decade “about which contractors were subject to drug and alcohol testing.” These amendments, which the agency said supercede all prior guidance on the subject of testing contractors, become effective on April 10.